6a larvae in April-September; mine often ending within the leaf sheath; larva: the 3 papillae of the rear spiraculum long and spreading like a hen’s foot; puparium with the rear spiracula well separated: Cerodontha silvatica

6b larvae in August-November, perhaps even later; mine usually confined to the leaf blade; larvae: one of the three papillae of the rear spiraculum very long and extending, the other 2 are folded in a half circle around the base of the first one; puparium: rear spiracula on a common base, touching each other: Cerodontha luzulae